scholarly journals Experimental Research on Foil Vibrations in a Gas Foil Bearing Carried Out Using an Ultra-High-Speed Camera

2021 ◽  
Vol 11 (2) ◽  
pp. 878
Author(s):  
Łukasz Breńkacz ◽  
Paweł Bagiński ◽  
Grzegorz Żywica
Keyword(s):  
High Speed ◽  
Numerical Models ◽  
Digital Camera ◽  
New Approach ◽  
Foil Bearings ◽  
Foil Bearing ◽  
Ultra High Speed ◽  
Supporting Layer ◽  
First Time ◽  
Further Development

The foil bearing consists of parts made of very thin, properly shaped foils. Usually, it is very difficult or even impossible to measure the vibrations of these elements during the bearing operation using traditional sensors. Therefore, the authors of this article have proposed an entirely new approach to this issue. This article discusses the analysis of vibrations of the structural supporting layer of a gas foil bearing at high rotational speeds. Instead of using a traditional method to measure the bearing journal movement, the measurement was performed using an ultra-high-speed digital camera. This type of measurement was used for the first time to analyse foil bearing displacement. It turned out that doing so can give a far more vibrant picture of what is happening in gas foil bearings during their operation. The article includes an analysis of foil vibrations. This phenomenon has already been analysed numerically, and this is the first time it has been analysed experimentally. The registered motion of the foils can be compared with the results obtained from numerical models, thus allowing their further development. One such comparison is shown in this article.

scholarly journals Rotor dynamic experimental investigation of an ultra-high-speed permanent magnet synchronous motor supported on a three-pad bidirectional gas foil bearing

2019 ◽  
Vol 11 (9) ◽  
pp. 168781401987536
Author(s):  
Wenjie Cheng ◽  
Zhikai Deng ◽  
Ling Xiao ◽  
Bin Zhong ◽  
Wenbo Duan
Keyword(s):  
Permanent Magnet ◽  
High Speed ◽  
Permanent Magnet Synchronous Motor ◽  
Synchronous Motor ◽  
Rotor System ◽  
Permanent Magnet Motors ◽  
Foil Bearings ◽  
Foil Bearing ◽  
Ultra High Speed ◽  
Rotor Dynamic

With a 10-kW, 120,000-r/min, ultra-high-speed permanent magnet synchronous motor taken as a prototype, experimental research is conducted on the rotor dynamic behaviours of a three-pad bidirectional gas foil bearing high-speed motor rotor system. Load-carrying properties of the three-pad bidirectional gas foil bearing are analysed, and natural frequencies of conical and parallel whirling modes of the elastically supported rotor are calculated based on an appropriate simplification to the stiffness and damping coefficients of the gas foil bearings. The prototype passes through a 90,000-r/min coast-down experiment. Experiments show that there are violent subsynchronous whirling motions that are evoked by the gas foil bearing–rotor system itself. The cause of shaft orbit drift is analysed, and the corresponding solution is put forward. The theoretical analysis and experimental results can offer a useful reference to the bearing–rotor system design of ultra-high-speed permanent magnet motors and its subsequent dynamic analysis.

Investigation of rotor–gas foil bearing system and its application for an ultra-high-speed permanent magnet synchronous motor

2021 ◽  
pp. 135065012110317
Author(s):  
Jiale Tian ◽  
Baisong Yang ◽  
Sheng Feng ◽  
Lie Yu ◽  
Jian Zhou
Keyword(s):  
Permanent Magnet ◽  
High Speed ◽  
Dynamic Performance ◽  
Permanent Magnet Synchronous Motor ◽  
Synchronous Motor ◽  
Rotating Speed ◽  
Foil Bearings ◽  
Foil Bearing ◽  
Ultra High Speed ◽  
Bearing System

In this study, an ultra-high-speed rotor–gas foil-bearing system is designed and applied to a permanent magnet synchronous motor. Gas foil journal bearings and gas foil thrust bearings are used to provide journal and axial support to the rotor, respectively. The bearings are analyzed theoretically considering the nonlinear deflection of the top foil, and the static and dynamic characteristics are obtained with which the rotor dynamic performances of the tested rotor are calculated using the finite element method. During the experiment, the permanent magnet synchronous motor can operate stably at 94,000 r/min, which demonstrates a great dynamic performance of the gas foil bearings and the stability that it provides to the entire system. The sub-synchronous vibration also occurs when the rotating speed reaches 60,000 r/min and as the speed keeps rising, the amplitude of such vibration increases, which will contribute to the destabilization of the rotor–gas foil-bearing system. Finally, the axial force of the rotor is calculated theoretically as well as measured directly by four micro force sensors mounted in the thrust end cover of the permanent magnet synchronous motor. The experimental results presented in this article are expected to provide a useful guide to the design and analysis of the rotor–gas foil-bearing system and high-speed permanent magnet synchronous motor.

EXPERIMENTAL INVESTIGATION OF A FOIL BEARING STRUCTURE WITH A POLYMER COATING UNDER STATIC LOADS

Tribologia ◽  
2018 ◽  
Vol 278 (2) ◽  
pp. 153-158 ◽  
Author(s):  
Grzegorz ŻYWICA ◽  
Paweł BAGIŃSKI
Keyword(s):  
Numerical Models ◽  
Static Characteristics ◽  
Static Loads ◽  
Foil Bearings ◽  
Metal Foils ◽  
Foil Bearing ◽  
Supporting Layer ◽  
Bearing Design ◽  
Bearing Structure ◽  
Very High

Gas foil bearings can operate at very high temperatures and rotational speeds. The operation under such conditions requires developing an appropriate bearing design, including the use of advanced material solutions. This article presents one of the basic stages of work on a new foil bearing, namely, experimental research on the structural supporting layer of such a bearing regarding its static loads. Tests of the bearing were carried out on a test rig specially prepared for this purpose. Changing the magnitude and direction of the load was possible. The elasto-damping elements of the bearing were made of thin metal foils. In addition, a layer of carefully selected polymer was applied onto one side of the top foil in order to protect the surface and reduce friction. Characteristics of the structure of the foil bearing were determined at various load variants after taking a series of measurements upon it. The conducted research has yielded much information about static characteristics of the structural supporting layer of a new foil bearing in which the top foil’s surface is covered with a layer of polymer. These results can be used, among other things, to optimise the bearing design and to verify numerical models.

An experimental investigation of a microturbine simulated rotor supported on multileaf gas foil bearings with backing bump foils

2017 ◽  
Vol 232 (9) ◽  
pp. 1169-1180 ◽  
Author(s):  
Bo Zhang ◽  
Shemiao Qi ◽  
Sheng Feng ◽  
Haipeng Geng ◽  
Yanhua Sun ◽  
...  
Keyword(s):  
High Speed ◽  
Preliminary Test ◽  
Journal Bearings ◽  
Rotating Machinery ◽  
System Stability ◽  
Test Rig ◽  
Thrust Bearings ◽  
Foil Bearings ◽  
Simulated System ◽  
First Time

Two multileaf gas foil journal bearings with backing bump foils and one set of gas foil thrust bearings were designed, fabricated, and used in a 100 kW class microturbine simulated rotor system to ensure stability of the system. Meanwhile, a preliminary test rig had been built to verify the simulated system stability. The rotor synchronous and subsynchronous responses were well controlled by using of the gas foil bearings. It is on the multileaf gas foil bearings with backing bump foils that the test was conducted and verified for the first time in open literatures. The success in the experiments shows that the design and fabrication of the rotor and the gas foil bearings can provide a useful guide to the development of the advanced high speed rotating machinery.

Rotordynamics Performance of Hybrid Foil Bearing Under Forced Vibration Input

2017 ◽  
Author(s):  
Daejong Kim ◽  
Brian Nicholson ◽  
Lewis Rosado ◽  
Garry Givan
Keyword(s):  
Impulse Response ◽  
High Speed ◽  
Load Capacity ◽  
Supply System ◽  
Forced Response ◽  
Experimental Results ◽  
Lateral Acceleration ◽  
Foil Bearings ◽  
Foil Bearing ◽  
Gas Supply

Foil bearings are one type of hydrodynamic air/gas bearings but with a compliant bearing surface supported by structural material that provides stiffness and damping to the bearing. The hybrid foil bearing (HFB) in this paper is a combination of a traditional hydrodynamic foil bearing with externally-pressurized air/gas supply system to enhance load capacity during the start and to improve thermal stability of the bearing. The HFB is more suitable for relatively large and heavy rotors where rotor weight is comparable to the load capacity of the bearing at full speed and extra air/gas supply system is not a major added cost. With 4,448N∼22,240N thrust class turbine aircraft engines in mind, the test rotor is supported by HFB in one end and duplex rolling element bearings in the other end. This paper presents experimental work on HFB with diameter of 102mm performed at the US Air force Research Laboratory. Experimental works include: measurement of impulse response of the bearing to the external load corresponding to rotor’s lateral acceleration of 5.55g, forced response to external subsynchronous excitation, and high speed imbalance response. A non-linear rotordynamic simulation model was also applied to predict the impulse response and forced subsynchronous response. The simulation results agree well with experimental results. Based on the experimental results and subsequent simulations, an improved HFB design is also suggested for higher impulse load capability up to 10g and rotordynamics stability up to 30,000rpm under subsynchronous excitation.

Rotordynamic Performance of a Shaft With Large Overhung Mass Supported by Foil Bearings

2016 ◽  
Vol 139 (4) ◽  
Author(s):  
Nguyen LaTray ◽  
Daejong Kim
Keyword(s):  
High Speed ◽  
Foil Bearings ◽  
Speed Test ◽  
Foil Bearing ◽  
Stable Conditions ◽  
Bending Mode ◽  
Mode Vibration ◽  
Lift Off ◽  
Compact Design ◽  
Bearing System

This work presents the theoretical and experimental rotordynamic evaluations of a rotor–air foil bearing (AFB) system supporting a large overhung mass for high-speed application. The proposed system highlights the compact design of a single shaft rotor configuration with turbomachine components arranged on one side of the bearing span. In this work, low-speed tests up to 45 krpm are performed to measure lift-off speed and to check bearing manufacturing quality. Rotordynamic performance at high speeds is evaluated both analytically and experimentally. In the analytical approach, simulated imbalance responses are studied using both rigid and flexible shaft models with bearing forces calculated from the transient Reynolds equation along with the rotor motion. The simulation predicts that the system experiences small synchronous rigid mode vibration at 20 krpm and bending mode at 200 krpm. A high-speed test rig is designed to experimentally evaluate the rotor–air foil bearing system. The high-speed tests are operated up to 160 krpm. The vibration spectrum indicates that the rotor–air foil bearing system operates under stable conditions. The experimental waterfall plots also show very small subsynchronous vibrations with frequency locked to the system natural frequency. Overall, this work demonstrates potential capability of the air foil bearings in supporting a shaft with a large overhung mass at high speed.

Influence of geometric parameters on the bump foil bearing performance

2019 ◽  
Vol 234 (7) ◽  
pp. 1017-1026
Author(s):  
Sadanand Kulkarni ◽  
Soumendu Jana
Keyword(s):  
Carrying Capacity ◽  
High Speed ◽  
System Development ◽  
Load Capacity ◽  
Radial Clearance ◽  
Load Carrying Capacity ◽  
Foil Bearings ◽  
Foil Bearing ◽  
Load Carrying ◽  
Lift Off

High-speed rotating system development has drawn considerable attention of the researchers, in the recent past. Foil bearings are one of the major contenders for such applications, particularly for high speed and low load rotating systems. In foil bearings, process fluid or air is used as the working medium and no additional lubricant is required. It is known from the published literature that the load capacity of foil bearings depend on the operating speed, viscosity of the medium, clearance, and stiffness of the foil apart from the geometric dimensions of the bearing. In case of foil bearing with given dimensions, clearance governs the magnitude of pressure developed, whereas stiffness dictates the change in radial clearance under the generated pressure. This article deals with the effect of stiffness, clearance, and its interaction on the bump foil bearings load-carrying capacity. For this study, four sets of foil bearings of the same geometry with two levels of stiffness and clearance values are fabricated. Experiments are carried out following two factor-two level factorial design approach under constant load and in each case, the lift-off speed is measured. The experimental output is analyzed using statistical techniques to evaluate the influence of parameters under consideration. The results indicate that clearance has the maximum influence on the lift-off speed/ load-carrying capacity, followed by interaction effect and stiffness. A regression model is developed based on the experimental values and model is validated using error analysis technique.

Vibration Mitigation of Rotors Suspended on Low-Cost Hybrid Gas Foil Bearing

2019 ◽  
Author(s):  
Kamal Kumar Basumatary ◽  
Karuna Kalita ◽  
Sashindra K. Kakoty ◽  
Seamus D. Garvey
Keyword(s):  
High Speed ◽  
Low Cost ◽  
Current Source ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Electromagnetic Actuators ◽  
Manufacturing Method ◽  
Foil Bearings ◽  
Foil Bearing ◽  
Small Series

Abstract The hybrid Gas Foil Bearings combining the Gas Foil Bearing and Active Magnetic Bearing is a possibility for application in high-speed turbomachinery and a few developments have been made in this context. As such, the cost of conventional Gas Foil Bearing increases due to its requirement of precise manufacturing method and the coating material for the top foil and bump foil. In case of Active Magnetic Bearing, the normal electrical arrangement includes a multiplicity of independently controlled current sources usually at least four drives per bearing which increases its cost. Therefore, the hybrid Gas Foil Bearing will have much higher cost. In this work, a new electrical arrangement for the electromagnetic actuators of the hybrid Gas Foil Bearing has been proposed. The new arrangement requires only two drives per bearing and the bias current has been provided (in the same set of windings) through a simple rectifier with small series choke and shunt capacitor. As the number of drives required is less, the proposed bearing will have low cost. Implementing the new approach, the force vectors are achieved using only two current-source drives whereas the usual conventional arrangement requires four such drives. Numerical simulations are performed to explore the capabilities of the low cost bearing.

The Dynamic Characteristics of a Turborotor Simulator Supported on Gas-Lubricated Foil Bearings—Part 3: Rotation in Foil Bearings of Reduced Length, With Starting and Stopping Unaided by External Pressurization

1972 ◽  
Vol 94 (3) ◽  
pp. 211-220 ◽  
Author(s):  
L. Licht
Keyword(s):  
Dynamic Characteristics ◽  
High Speed ◽  
Experimental Methods ◽  
Wear Characteristics ◽  
Foil Bearings ◽  
Foil Bearing

Experiments and analysis, reported in detail in references [1] through [5], demonstrated that high-speed rotors, supported by foil bearings, were free from whirl-instability and sensitivity to excitation at frequency equal one half the speed of rotation. It was shown also that the foil bearing could accommodate thermal and geometrical distortions, combining this attribute with excellent wipe-wear characteristics and tolerance of particles. The present investigation was directed toward the solution of two important problems: (a) the reduction of foil bearing length without detriment to rotor performance, and (b) the elimination of the foil-lift system and attainment of multiple start-stops without the aid of external pressurization. A description of experimental methods, which lead to the realization of the foregoing objectives, is given.

scholarly journals The Dynamic Characteristics of a Turborotor Simulator Supported on Gas-Lubricated Foil Bearings—Part 2: Operation With Heating and Thermal Gradients

1970 ◽  
Vol 92 (4) ◽  
pp. 650-659 ◽  
Author(s):  
L. Licht
Keyword(s):  
Dynamic Characteristics ◽  
High Speed ◽  
Elevated Temperatures ◽  
Load Capacity ◽  
Temperature Gradients ◽  
Thermal Gradients ◽  
Foil Bearings ◽  
Foil Bearing ◽  
Geometrical Imperfections ◽  
The Stability

A high-speed rotor, supported by gas-lubricated foil bearings, is free from self-excited whirl and displays no loss of load capacity when vibrated at frequency equal half the rotational speed [1]. It is demonstrated here that in addition to tolerance of geometrical imperfections, misalignment, and foreign particles [3, 4], the foil bearing performs well at elevated temperatures and accommodates appreciable temperature gradients. The foil bearing is endowed with superior wipe-wear characteristics, and the flexibility of the foil accounts not only for the stability of the foil bearing but also for its forgiveness with respect to distortion, contamination, and contact.

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